Electrically controlled dielectric panel lens

ABSTRACT

The apparatus and process for phase shifting a radiated microwave includes passing the microwave beam through a dielectric panel in which is imbedded at least one plane network of conductive leads running parallel with the electric field of the incident wave. Switches mounted on each lead are spaced from each other at distances less than two wavelengths in the dielectric material, of the incident energy. By these switches, the leads may be divided in little sections.

01--.02..r3 OR 3,708,796

United States Patent [1 1 1111 3,708,796 Gilbert 14 -1 Jan. 2, 197 3 541ELECTRICALLY CONTROLLED 2,867,801 1/1959 Mariner et al ..343/756DIELECTRIC PANEL LENS 3,354,461 ll/l967 Kelleher ....343/7s4 3,392,3937/1968 Spitz ..343/754 [76] Inventor: Bony Gilbert, 67, BoulevardGallief", issy, France Primary Examiner-Eli Lieberman [22] Filed; Oct15, 1970 Attorney-Young & Thompson [21] Appl. No.2 81,062 57 ABSTRACTThe apparatus and process for phase shifting a [30] Fomgn ApplicationPrion Data radiated microwave includes passing the microwave Oct. 15,I969 France ..6935239 beam through a dielectric Panel in which isimhedded at least one plane network of conductive leads running [52] US.Cl. ..343/754, 343/756, 343/909 Parallel with the tric fiel f theincident wave. [51] Int. Cl. ..l-l01q 19/06 Switches u ted on each leadare spaced from each [58] Field f S ar h 343/757, 754,755, 354, 909,other at distances less than two wavelengths in the 343/756 dielectricmaterial, of the incident energy. By these switches, the leads may bedivided in little sections. [56] References Cited 3 Claims, 6 DrawingFigures UNITED STATES PATENTS 3,276,023 8/1966 Dome et al ..V....343/754PATENTEDJMI 2191s "law CoNTRoL VOLT; FIG. 1

FIG.3

CONTROL VOLT.

ii A A M \12 34 FIG. 4

Flee

Ga aser Aa/vv Arr):

ELECTRICALLY CONTROLLED DIELECTRIC PANEL LENS BACKGROUND OF THEINVENTION This invention relates to a process for phase-shifting, asrequired, a beam emitted by a microwave radiating source, and also tothe applications of such process to the design and development ofstructures capable of changing the direction of a beam from a microwavesource, such structures being adapted for use as electronic-scanningequipment.

A process for focusing or deflecting a wave from a microwave radiatingsource is already known in the prior art and consists in interposing inthe wave path a lens or active reflector consisting of similarjuxtaposed elements, each consisting of a receiving antenna and awave-guide. The deflection brought about by the lens or active reflectoris altered by the effect of phase-shifters mounted in each wave-guide.

This process has many drawbacks which prevent it from vying successfullywith known mechanicalscanning devices. One of these drawbacks is thatthe very small size of the juxtaposed antennas and waveguides making upthe active lenses require very close manufacturing tolerances and alossless material. It

, should also be pointed out that the control leads of all theseantennas and wave-guides are very large in number and that adjusting andchecking them is a tricky business.

The main object of the present invention is to eliminate the drawbacksof the previous process and to provide a process for changingeffectively, as required, the direction of a beam emitted by a microwaveradiating source. This process also eradicates the constraints ofmechanical scanning.

Another object of the present invention is to provide a process forphase-shifting, as required, the incoming beam from a microwaveradiating source by interposing one or several dielectric panels in thepath of the electromagnetic wave. Each panel includes one or severalplane networks of conductive leads running parallel with the electricfield of the incident wave which can be connected and disconnected, asrequired, by means of switches located on these leads at distances lessthan 2k, where k is the wavelength, in the dielectric material, of theradiated incident energy.

A further object of the present invention is to provide an apparatus andprocess for phase-shifting a beam emitted from a microwave radiatingsource which includes passing the beam through a dielectric panel andconnecting and disconnecting, as required, each conducting lead byswitches located thereon and spaced, atdistances less than twice thewave-length, in the dielectric material, of the radiated microwaveenergy; these leads constituting a plane network imbedded in the panelsdielectric and parallel with the field of the incident wave.

These and other objects of the present invention will be readilyapparent upon a consideration of the following specification taken inconjunction with the accompanying drawings in which:

FIG. 1 is a block diagram illustrating a phase shifting apparatus of thepresent invention;

FIG. 2 is a view in front elevation illustrating one of the dielectricpanels of FIG. 1;

FIG. 3 illustrates two spaced dielectric panels having orthogonallyarranged conductive networks;

reflector constructed in accordance with the present invention; and

FIG. 6 illustrates a second embodiment of an active reflectorconstructed in accordance with the present invention.

For purposes of this invention, a panel is any element with a plane, orlocally like surface, which lies throughout to a plane with respect tothe wave-length of the radiated microwave energy.

It follows that the leads forming the plane network imbedded in thedielectric of a panel likened to a plane are to be located at theintersections of the panel in planes parallel with the electric fieldand this, throughout the said panel.

The conductive leads making up the plane networks imbedded in thedielectric and which can be, as required, joined or divided in sectionsby switches located thereon, are selected so as to constituteself-inductive barriers from the standpoint of microwaves. These leadsare arranged to-produce any ofthe effects, known of the prior art,obtainable by setting conductive leads in dielectric panels.

In the aforesaid processes of the invention, the switches are onconductive leads constituting the plane networks, the switchespreferably being spaced apart, within the dielectric at one quarter ofthe wavelength, in the dielectric material, of the radiated microwaveenergy.

The panels employed to implement the processes of the invention (FIGS. 1and 2) consist of dielectric sheets 10 in which are imbedded planenetworks of conductive leads 12 which may be interrupted or not, asrequired, by means of switches 14 located on the leads in the dielectricand spaced less than twice the wavelength from the radiated microwaveenergy. These leads constitute a plane network imbedded in thedielectric of the panel which is parallel with the field 16 of theincident wave from a microwave source 18.

When interposing concurrently several panels in the path of amicrowavewave, these panels may be positioned one behind the other in the path ofthe microwave and suitably apart from each other while, of course,leaving the respective networks of leads, (connected and disconnected asrequired) parallel with the electric field of the incident wave.Alternatively, the panels may be positioned with the sides thereof,which are parallel to the networks of leads, contacting, the networks ofleads being also parallel with the electric field of the incident wave.

Rather than setting several panels one behind the other, according tothe invention, it is also feasible to devise a single multiple panel byimbedding in a dielectric sheet comprising several successive planes,several planar networks of leads which can be connected and disconnectedas required.

When interposing concurrently several panels, according to the processof the invention, across the path of two cross-polarized microwaves thatcan be phaseshifted as required, the networks of leads, connected anddisconnected as required, must be placed so as to be parallel with theelectric fields of both incident waves, i.e., normal to one another asillustrated in FIG. 3. Herepanels 19 and 20 are arranged with orthogonalleads l2.

The switches spaced on the leads and imbedded in the dielectric panelsare controlled either separately or, preferably, in groups. Electricallyor electronically controlled switches are preferred, and each switch iscontrolled either through its relevant lead, or leads normal to theelectric field of the incident wave.

The switches 14 may consist of diodes controlled by a voltage sufficientto make them conductive or not. The diodes in series on the same leadare mounted in the same direction and concurrently controlled by thesame voltage on input 22. Of course, several rows of diodes, of one orseveral panels, can be controlled concurrently by the same voltagesource 24 as illustrated in FIG. 1.

To do away with the reflections caused by interposing the dielectricpanels, according to the process of the invention, across the path ofthe beam, all that is required is to space apart two or several parallelpanels as previously described in such a way that the reflectionsarising from each panel combine in regard to amplitudes and relativephases such that there is no longer any reflected wave. This may beachieved using the socalled sandwich technique known to the art.

To do away with the reflections, it is also possible, as known in theprior art, to make up the panel from dielectric sheets whose width is ahalf-wavelength multiple, within the dielectric, from the radiatedmicrowave energy. This is done, as stated above, by imbedding, in thissheet of specific thickness, one or several networks of conductiveleads, connected and disconnected as required, and arranged in planesparallel with the electric field of the incident wave.

The applicant has discovered that the effect on the phase shift of anincident wave of a planar network of parallel leads, imbedded in adielectric panel, changes when the leads are interrupted at intervalssufficiently close that there are no longer any induced currents in theleads. For instance, when the state of a dielectric panel including aplanar network of parallel conductive leads, selected and positionedacross the path of the incident wave so as not to give rise to anyreflection and virtually no phase shift thereon, is altered throughinterruption of the conductive leads at intervals of one quarterwavelength, in the dielectric material, a substantial phase shift of thesaid incident wave is brought about.

By way of non-limitative example, a sandwich panel is describedhereunder which pennits implementing the process for changing, asrequired, the phase shift of a beam incoming from a microwave radiatingsource.

In two sheets of fiber-glass-reinforced polyester, each 6.5 mm thick,forming a laminate whose dielectric constant is 3.5, copper leads of 0.5mm gauge were imbedded at mid-thickness of each sheet to a pitch of 30mm. Standard silicon diodes were inserted and spaced to a pitch of 26 mmin those leads, their connections being soldered to the end of thesections of the leads. Such diodes were all connected in the samedirection on all leads, thus making up a circuit which becomesconductive when supplied with a -volt potential difference at the properpolarity and, on reversal of the latter, this circuit becomesnon-conductive. This diode control voltage is handily applied to thetips of the leads which are on the side of the panel and were made toprotrude for this very purpose.

These two sheets, so fitted with wired-on diodes, are identical and werespaced parallel 31 mm apart; the leads being likewise parallel.

Such a panel, as with any sandwich panel, is matched at all times, i.e.,no objectionable spurious reflections occur irrespective of the statethe diodes in the sheet are in, provided, however, that in both sheets,the corresponding diodes are in the same state.

The panel operates as follows. The phase shift varies according to thestate of the diodes in both sheets. lt peaks when the diodes are cut offand drops to a minimum when the diodes are conducting. The phase shiftis not identical throughout the surface of the panel when some banks ofdiodes are cut off and some conducting. The phase shift peaks whereportions of the wave have come across cut-off banks and is minimalacross conducting banks. This shows how it is possible, in accordancewith the teachings of the invention, to control the phase shift of anincident wave with such a panel.

When a 3 GHz wave passes through this panel, the phase shift is when thediodes are cut off and 6 when conducting.

The present invention provides a phase shifting unit which is muchsimplified and has tolerance limits which are definitely less stringentthan known units. The panels and sheets are readily assembled rigidlyand fully enclosed. Losses in the dielectric can easily be made verysmall.

The outer connections to the radiating unit are fewer, and the leadsimbedded in the dielectric fulfil two functions; function control ofdiodes and function microwave components. The unit is fully integrated,there being no need to subdivide it into several modules. in addition,with the diodes being connected in series on each lead, the controlcurrents are low, and the microwave energy flowing in the diodes matchesthe energy required for correcting the disconnections. This accounts forbut a small portion of the aggregate energy conveyed by the incidentwave. The upshot is that the losses ascribable to the diodes are verysmall, even when using standard and inexpensive diodes.

The principles and structures heretofore described can be employed toform lenses which are active in the plane normal to the network ofconnected and interrupted leads, and which provide focusing anddeflecting in all planes and active reflectors.

Provision of such an active lens, according to the invention, isachieved merely by forming a device whereby the phase shift of anincident wave is varied locally from 0 to 360 in as small increments asrequired. This is accomplished by the proper selection of dielectricpanels of a given thickness, including leads interrupted, as required,by the banks of diodes described above, and by setting a number of suchpanels of the type illustrated by FIG. 2, such phase shifts of theincident wave are brought about, as required, from 0 to 360. A computermay be employed to control the switching voltages and accomplish phaseshifting from 0 to 360.

The incident wave is split into as many parallel strips as there areleads including banks of diodes. The phase shift is uniform on eachstrip and may vary from one to the other and, by acting upon the diodescontrol voltage, the incident wave can be focused or deflected, or

both in the plane normal to the disconnected leads. Thus is achieved anactive lens normal to the leads.

To constitute an active lens that will focus and deflect in all planes,all that is needed is to set two active lenses 26 and 28, as describedabove, one behind the other so that the leads of the former be normal tothe leads of the other and both lenses be separated by a device 30operative to rotate the polarization of the incident wave through 90'(FIG. 4). It follows that both focusing and deflection can be separatefunctions and that a conventional device, such as a reflector or astandard lens can take care of focusing.

An active reflector, according to the invention, is readily constructedby the provision of an active lens 32 formed from a plurality of panelsarranged one behind the other as described above and, setting the activelens in front of a mirror 34 as illustrated by FIG. 5.

Another active reflector is also achievable, according to the invention,by using one or several dielectric panels 36 comprising at least twoplanar networks 38 and 40 of perpendicular conductive leads, and settingthis special-type panel opposite a mirror including arotatory-polarization device 42 (FIG. 6). The leads 38 parallel theelectric field of the incident wave while the leads 40 are parallel,after reflection, with the electric field of the wave.

Iclaim: t

l. A lens apparatus for phase shifting a wave transmitted by a microwaveradiating source, comprising at least one dielectric panel interposedacross the path of the beam of microwave energy, said at least onedielectric panel including at least one network of conductive leadsimbedded therein, throughout the panel, and located in planes parallelto the electric field vector of the incident wave, and switches mountedon each said conductive lead and spaced apart thereon by a distance nomore than twice the wavelength, in the dielectric material, of theradiated incident energy, allowing the conductive leads to be eitherdivided in sections or not divided along the whole length of the panel,said dielectric panel having a thickness which is a multiple of a halfwavelength, in the dielectric material, of the radiated microwaveenergy, to prevent any reflection of the incident wave.

2. A lens apparatus for phase shifting a wave transmitted by a microwaveradiating source, comprising at least one dielectric panel interposedacross the path of the beam of microwave energy, said at least onedielectric panel including at least one network of conductive leadsimbedded therein, throughout the panel, and located in planes parallelto the electric field vector of the incident wave, and switches mountedon each said conductive lead and spaced apart thereon by a distance nomore than twice the wavelength, in the dielectric material, of theradiated incident energy, allowing the conductive leads to be eitherdivided in sections or not divided along the whole length of the panel,said switches including diodes controlled by a control voltage to rendersuch diodes conductive, said control voltage being supplied to thediodes through said conductive leads, there being a plurality of saiddielectric panels placed behind one another across the path of the beam,said control voltage being selectively applied to each conductive leadto vary the phase shifting of said wave from 0 to 360.

3. A lens apparatus as clarmed in claim 2, 1111011 includes a first setof said dielectric panels arranged behind one another across the path ofthe incident beam, a polarization device operating to rotate through theplane of polarization of the wave and a second set of dielectric panelsarranged behind one another across the path of the beam, the conductiveleads of said second set of panels being orthogonal to the conductiveleads of the first set of panels.

I II

1. A lens apparatus for phase shifting a wave transmitted by a microwaveradiating source, comprising at least one dielectric panel interposedacross the path of the beam of microwave energy, said at leAst onedielectric panel including at least one network of conductive leadsimbedded therein, throughout the panel, and located in planes parallelto the electric field vector of the incident wave, and switches mountedon each said conductive lead and spaced apart thereon by a distance nomore than twice the wavelength, in the dielectric material, of theradiated incident energy, allowing the conductive leads to be eitherdivided in sections or not divided along the whole length of the panel,said dielectric panel having a thickness which is a multiple of a halfwavelength, in the dielectric material, of the radiated microwaveenergy, to prevent any reflection of the incident wave.
 2. A lensapparatus for phase shifting a wave transmitted by a microwave radiatingsource, comprising at least one dielectric panel interposed across thepath of the beam of microwave energy, said at least one dielectric panelincluding at least one network of conductive leads imbedded therein,throughout the panel, and located in planes parallel to the electricfield vector of the incident wave, and switches mounted on each saidconductive lead and spaced apart thereon by a distance no more thantwice the wavelength, in the dielectric material, of the radiatedincident energy, allowing the conductive leads to be either divided insections or not divided along the whole length of the panel, saidswitches including diodes controlled by a control voltage to render suchdiodes conductive, said control voltage being supplied to the diodesthrough said conductive leads, there being a plurality of saiddielectric panels placed behind one another across the path of the beam,said control voltage being selectively applied to each conductive leadto vary the phase shifting of said wave from 0* to 360*.
 3. A lensapparatus as claimed in claim 2, which includes a first set of saiddielectric panels arranged behind one another across the path of theincident beam, a polarization device operating to rotate through 90* theplane of polarization of the wave and a second set of dielectric panelsarranged behind one another across the path of the beam, the conductiveleads of said second set of panels being orthogonal to the conductiveleads of the first set of panels.